【从零开始的Qt开发指南】（二十一）Qt 网络编程封神指南：UDP/TCP/HTTP 全场景实战

QT += core gui network  // 新增network模块

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QUdpSocket>
#include <QNetworkDatagram>
#include <QMessageBox>
#include <QDebug>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

private slots:
    // 处理收到的数据报
    void processRequest();

private:
    Ui::Widget *ui;
    QUdpSocket *udpSocket;  // UDP Socket对象
    const quint16 SERVER_PORT = 9090;  // 服务器端口
};

#endif // WIDGET_H

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    this->setWindowTitle("UDP回显服务器（端口：9090）");
    ui->listWidget->setReadOnly(true);

    // 1. 实例化UDP Socket
    udpSocket = new QUdpSocket(this);

    // 2. 绑定端口（监听所有网卡的9090端口）
    bool bindSuccess = udpSocket->bind(QHostAddress::Any, SERVER_PORT);
    if (!bindSuccess)
    {
        QMessageBox::critical(this, "启动失败", "端口绑定失败：" + udpSocket->errorString());
        return;
    }

    // 3. 连接信号槽：有数据到达时触发processRequest
    connect(udpSocket, &QUdpSocket::readyRead, this, &Widget::processRequest);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::processRequest()
{
    // 循环接收所有待处理的数据报
    while (udpSocket->hasPendingDatagrams())
    {
        // 1. 接收数据报
        QNetworkDatagram datagram = udpSocket->receiveDatagram();
        if (datagram.isValid())
        {
            // 2. 解析数据报信息
            QString clientIp = datagram.senderAddress().toString();
            quint16 clientPort = datagram.senderPort();
            QString requestData = QString::fromUtf8(datagram.data());

            // 3. 显示日志
            QString log = QString("[%1:%2] 收到请求：%3")
                          .arg(clientIp)
                          .arg(clientPort)
                          .arg(requestData);
            ui->listWidget->addItem(log);

            // 4. 回显数据（原样返回给客户端）
            QNetworkDatagram responseDatagram(
                requestData.toUtf8(),  // 响应数据
                datagram.senderAddress(),  // 客户端IP
                datagram.senderPort()     // 客户端端口
            );
            udpSocket->writeDatagram(responseDatagram);

            // 5. 显示响应日志
            QString responseLog = QString("[%1:%2] 发送响应：%3")
                                 .arg(clientIp)
                                 .arg(clientPort)
                                 .arg(requestData);
            ui->listWidget->addItem(responseLog);
        }
    }
}

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QUdpSocket>
#include <QNetworkDatagram>
#include <QDebug>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

private slots:
    // 发送按钮点击槽函数
    void on_pushButton_clicked();
    // 处理服务器响应
    void processResponse();

private:
    Ui::Widget *ui;
    QUdpSocket *udpSocket;  // UDP Socket对象
    const QString SERVER_IP = "127.0.0.1";  // 服务器IP
    const quint16 SERVER_PORT = 9090;       // 服务器端口
};

#endif // WIDGET_H

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    this->setWindowTitle("客户端");
    ui->listWidget->setReadOnly(true);

    // 1. 实例化UDP Socket
    udpSocket = new QUdpSocket(this);

    // 2. 连接信号槽：有响应数据到达时触发processResponse
    connect(udpSocket, &QUdpSocket::readyRead, this, &Widget::processResponse);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_pushButton_clicked()
{
    // 1. 获取输入框内容
    QString sendData = ui->lineEdit->text().trimmed();
    if (sendData.isEmpty())
    {
        ui->listWidget->addItem("错误：发送数据不能为空！");
        return;
    }

    // 2. 构造UDP数据报
    QNetworkDatagram datagram(
        sendData.toUtf8(),  // 发送数据
        QHostAddress(SERVER_IP),  // 服务器IP
        SERVER_PORT               // 服务器端口
    );

    // 3. 发送数据报
    qint64 sendBytes = udpSocket->writeDatagram(datagram);
    if (sendBytes != -1)
    {
        // 4. 显示发送日志
        QString log = QString("客户端说：%1").arg(sendData);
        ui->listWidget->addItem(log);
        // 清空输入框
        ui->lineEdit->clear();
    }
    else
    {
        ui->listWidget->addItem("发送失败：" + udpSocket->errorString());
    }
}

void Widget::processResponse()
{
    // 接收服务器响应
    while (udpSocket->hasPendingDatagrams())
    {
        QNetworkDatagram datagram = udpSocket->receiveDatagram();
        if (datagram.isValid())
        {
            QString responseData = QString::fromUtf8(datagram.data());
            QString log = QString("[服务器说]：%1").arg(responseData);
            ui->listWidget->addItem(log);
        }
    }
}

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTcpServer>
#include <QTcpSocket>
#include <QMessageBox>
#include <QDebug>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

private slots:
    // 处理新客户端连接
    void onNewConnection();
    // 处理客户端发送的数据
    void onReadyRead();
    // 处理客户端断开连接
    void onDisconnected();

private:
    Ui::Widget *ui;
    QTcpServer *tcpServer;  // TCP服务器对象
    const quint16 SERVER_PORT = 9090;  // 服务器端口
};

#endif // WIDGET_H

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    this->setWindowTitle("服务器");
    ui->listWidget->setReadOnly(true);

    // 1. 实例化TCP服务器
    tcpServer = new QTcpServer(this);

    // 2. 监听所有网卡的9090端口
    bool listenSuccess = tcpServer->listen(QHostAddress::Any, SERVER_PORT);
    if (!listenSuccess)
    {
        QMessageBox::critical(this, "启动失败", "服务器启动失败：" + tcpServer->errorString());
        return;
    }

    // 3. 连接信号槽：有新客户端连接时触发onNewConnection
    connect(tcpServer, &QTcpServer::newConnection, this, &Widget::onNewConnection);
}

Widget::~Widget()
{
    // 关闭所有客户端连接
    foreach (QTcpSocket *socket, tcpServer->findChildren<QTcpSocket*>())
    {
        socket->close();
        socket->deleteLater();
    }
    // 关闭服务器
    tcpServer->close();
    delete ui;
}

void Widget::onNewConnection()
{
    // 1. 获取新客户端连接的Socket
    QTcpSocket *clientSocket = tcpServer->nextPendingConnection();
    if (!clientSocket)
    {
        ui->listWidget->addItem("警告：获取客户端连接失败！");
        return;
    }

    // 2. 获取客户端信息
    QString clientIp = clientSocket->peerAddress().toString();
    quint16 clientPort = clientSocket->peerPort();
    QString log = QString("[%1:%2] 客户端上线！").arg(clientIp).arg(clientPort);
    ui->listWidget->addItem(log);

    // 3. 连接客户端Socket的信号槽
    // 数据到达时触发onReadyRead
    connect(clientSocket, &QTcpSocket::readyRead, this, &Widget::onReadyRead);
    // 连接断开时触发onDisconnected
    connect(clientSocket, &QTcpSocket::disconnected, this, &Widget::onDisconnected);
    // 自动销毁Socket对象
    connect(clientSocket, &QTcpSocket::destroyed, [=]() {
        ui->listWidget->addItem(QString("[%1:%2] Socket对象已销毁").arg(clientIp).arg(clientPort));
    });
}

void Widget::onReadyRead()
{
    // 1. 获取发送数据的客户端Socket
    QTcpSocket *clientSocket = qobject_cast<QTcpSocket*>(sender());
    if (!clientSocket)
        return;

    // 2. 读取数据（UTF-8编码）
    QByteArray data = clientSocket->readAll();
    QString requestData = QString::fromUtf8(data);

    // 3. 获取客户端信息
    QString clientIp = clientSocket->peerAddress().toString();
    quint16 clientPort = clientSocket->peerPort();

    // 4. 显示请求日志
    QString requestLog = QString("[%1:%2] 收到请求：%3").arg(clientIp).arg(clientPort).arg(requestData);
    ui->listWidget->addItem(requestLog);

    // 5. 回显数据（原样返回）
    clientSocket->write(data);

    // 6. 显示响应日志
    QString responseLog = QString("[%1:%2] 发送响应：%3").arg(clientIp).arg(clientPort).arg(requestData);
    ui->listWidget->addItem(responseLog);
}

void Widget::onDisconnected()
{
    // 1. 获取断开连接的客户端Socket
    QTcpSocket *clientSocket = qobject_cast<QTcpSocket*>(sender());
    if (!clientSocket)
        return;

    // 2. 获取客户端信息
    QString clientIp = clientSocket->peerAddress().toString();
    quint16 clientPort = clientSocket->peerPort();

    // 3. 显示下线日志
    QString log = QString("[%1:%2] 客户端下线！").arg(clientIp).arg(clientPort);
    ui->listWidget->addItem(log);

    // 4. 释放Socket资源（延迟销毁）
    clientSocket->deleteLater();
}

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTcpSocket>
#include <QAbstractSocket>
#include <QDebug>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

private slots:
    // 发送按钮点击槽函数
    void on_pushButton_clicked();
    // 连接建立成功槽函数
    void onConnected();
    // 接收服务器响应槽函数
    void onReadyRead();
    // 连接断开槽函数
    void onDisconnected();
    // 错误处理槽函数
    void onErrorOccurred(QAbstractSocket::SocketError error);

private:
    Ui::Widget *ui;
    QTcpSocket *tcpSocket;  // TCP Socket对象
    const QString SERVER_IP = "127.0.0.1";  // 服务器IP
    const quint16 SERVER_PORT = 9090;       // 服务器端口
};

#endif // WIDGET_H

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    this->setWindowTitle("客户端");
    ui->listWidget->setReadOnly(true);

    // 1. 实例化TCP Socket
    tcpSocket = new QTcpSocket(this);

    // 2. 连接信号槽
    connect(tcpSocket, &QTcpSocket::connected, this, &Widget::onConnected);
    connect(tcpSocket, &QTcpSocket::readyRead, this, &Widget::onReadyRead);
    connect(tcpSocket, &QTcpSocket::disconnected, this, &Widget::onDisconnected);
    connect(tcpSocket, &QTcpSocket::errorOccurred, this, &Widget::onErrorOccurred);

    // 3. 连接服务器
    tcpSocket->connectToHost(SERVER_IP, SERVER_PORT);
}

Widget::~Widget()
{
    // 关闭连接
    if (tcpSocket->state() == QAbstractSocket::ConnectedState)
    {
        tcpSocket->disconnectFromHost();
    }
    delete ui;
}

void on_pushButton_clicked()
{
    // 1. 检查连接状态
    if (tcpSocket->state() != QAbstractSocket::ConnectedState)
    {
        ui->listWidget->addItem("连接服务器出错！");
        return;
    }

    // 2. 获取输入框内容
    QString sendData = ui->lineEdit->text().trimmed();
    if (sendData.isEmpty())
    {
        ui->listWidget->addItem("错误：发送数据不能为空！");
        return;
    }

    // 3. 发送数据（UTF-8编码）
    qint64 sendBytes = tcpSocket->write(sendData.toUtf8());
    if (sendBytes != -1)
    {
        // 4. 显示发送日志
        QString log = QString("客户端说：%1").arg(sendData);
        ui->listWidget->addItem(log);
        // 清空输入框
        ui->lineEdit->clear();
    }
    else
    {
        ui->listWidget->addItem("发送失败：" + tcpSocket->errorString());
    }
}

void Widget::onConnected()
{
    // 连接建立成功日志
}

void Widget::onReadyRead()
{
    // 1. 读取服务器响应数据
    QByteArray data = tcpSocket->readAll();
    QString responseData = QString::fromUtf8(data);

    // 2. 显示响应日志
    QString log = QString("[服务器说]：%1").arg(responseData);
    ui->listWidget->addItem(log);
}

void Widget::onDisconnected()
{
    ui->listWidget->addItem("连接已断开！");
}

void Widget::onErrorOccurred(QAbstractSocket::SocketError error)
{
    // 错误日志
    QString errorLog = QString("错误：%1").arg(tcpSocket->errorString());
    ui->listWidget->addItem(errorLog);
}

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QUrl>
#include <QDebug>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class Widget : public QWidget
{
    Q_OBJECT

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();

private slots:
    // 发送GET请求按钮点击槽函数
    void on_pushButton_clicked();
    // 响应接收完成槽函数
    void onReplyFinished();

private:
    Ui::Widget *ui;
    QNetworkAccessManager *networkManager;  // HTTP请求管理器
};

#endif // WIDGET_H

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    ui->plainTextEdit->setReadOnly(true);
    // 默认URL：百度首页
    ui->lineEdit->setText("http://www.baidu.com");

    // 1. 实例化QNetworkAccessManager（全局唯一即可）
    networkManager = new QNetworkAccessManager(this);
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_pushButton_clicked()
{
    // 1. 获取URL
    QString urlStr = ui->lineEdit->text().trimmed();
    if (urlStr.isEmpty())
    {
        ui->plainTextEdit->setPlainText("错误：URL不能为空！");
        return;
    }
    QUrl url(urlStr);
    if (!url.isValid())
    {
        ui->plainTextEdit->setPlainText("错误：无效的URL！");
        return;
    }

    // 2. 构造HTTP请求
    QNetworkRequest request(url);
    // 设置请求头：模拟浏览器（可选，部分服务器需验证User-Agent）
    request.setHeader(QNetworkRequest::UserAgentHeader, 
                      "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36");

    // 3. 发送GET请求
    QNetworkReply *reply = networkManager->get(request);
    // 连接信号槽：响应接收完成时触发onReplyFinished
    connect(reply, &QNetworkReply::finished, this, &Widget::onReplyFinished);
    // 自动销毁reply对象
    connect(reply, &QNetworkReply::destroyed, [=]() {
        ui->statusbar->clearMessage();
    });
}

void Widget::onReplyFinished()
{
    // 1. 获取响应对象
    QNetworkReply *reply = qobject_cast<QNetworkReply*>(sender());
    if (!reply)
        return;

    // 2. 处理响应
    QString responseData;
    if (reply->error() == QNetworkReply::NoError)
    {
        // 响应成功：读取响应体（UTF-8编码）
        QByteArray data = reply->readAll();
        responseData = QString::fromUtf8(data);
    }
    else
    {
        // 响应失败：显示错误信息
        responseData = QString("请求失败：%1").arg(reply->errorString());
    }

    // 3. 显示响应数据
    ui->plainTextEdit->setPlainText(responseData);

    // 4. 释放资源
    reply->deleteLater();
}

#include <QTextCodec>
// GBK转UTF-8
QTextCodec *codec = QTextCodec::codecForName("GBK");
QString gbkStr = codec->toUnicode(data);
QByteArray utf8Data = gbkStr.toUtf8();